This invention relates to motor vehicles that have multiple fuel tanks for holding liquid fuel that is consumed by an engine to propel the vehicle. The invention is particularly concerned with a method and system for balancing fuel levels in the tanks by selectively returning return fuel from the engine to the tanks by using data from fuel level senders at the tanks to determine when, and to which tank, return fuel should be returned for correcting imbalance between tanks.
Certain motor vehicles have multiple fuel tanks for holding liquid fuel that is consumed by an engine to power the vehicle. An example of such a vehicle is a medium or heavy truck that has a right fuel tank on the right side of the truck chassis and a left fuel tank on the left side. The engine is disposed more or less centrally of the chassis and forward of the fuel tanks. For any of various reasons, it may be considered desirable to maintain the respective fuel level in each tank more or less equal to that in the opposite tank, thereby achieving at least an approximate balance of fuel between the tanks.
Motor vehicle fuel systems having various means for drawing fuel from, and returning fuel to, multiple fuel tanks are disclosed in a number of U.S. patents. Examples of such fuel systems may be found in U.S. Pat. Nos. 4,930,537; 5,163,466; 5,555,873; and 5,960,809.
Those patents are concerned with switching a tank into and out of the fuel system, manually or automatically, and/or with correcting imbalance between tanks at opposite sides of the vehicle. None however is seen to provide dual-draw, dual-return operation when substantial balance exists between dual tanks while by providing dual-draw, single-return operation to correct indicated imbalance by disallowing return fuel to enter the tank indicated to have the greater level of fuel.
Two presently preferred embodiments of the invention are disclosed herein.
One embodiment employs two normally open solenoid valves, each selectively operable, by energizing its solenoid, to disallow return fuel flow to the respective tank when the respective tank has an indicated fuel level sufficiently greater than that of the other tank to indicate imbalance that needs correction.
Accordingly, one aspect of the present invention relates to a motor vehicle having a dual tank fuel system that provides dual-draw from, and dual-return to, the tanks as long as substantial fuel balance exists between them. When fuel imbalance is indicted, the system provides dual-draw, single-return by disallowing return fuel flow to the tank having a higher indicated fuel level.
The other embodiment employs a solenoid-operated diverter valve that selectively diverts the entire return fuel flow to one tank to the exclusion of the other tank. When the fuel level in that one tank becomes sufficiently greater than that in the other tank to indicate imbalance that needs correction, the diverter valve switches the entire return flow back to the other tank. Once the fuel level in the latter tank has risen to exceed that in the former tank by an amount indicating an imbalance that needs correction, the valve switches the entire return flow back to the former tank.
One generic aspect of the present invention relates to a motor vehicle comprising a fuel-consuming engine for powering the vehicle and a fuel system for fueling the engine. The fuel system comprises multiple fuel tanks, each for holding liquid fuel for the engine, and for each tank, a respective sender for providing data representing the level of liquid fuel in the respective tank. A pump draws fuel from the tanks through respective fuel draw conduits communicated to the respective tanks and delivers the drawn fuel to the engine. Excess fuel is returned from the engine to each tank through a respective fuel return conduit, with a valve mechanism controlling return fuel flow through the fuel return conduits to the tanks. A processor processes the data from the respective senders and causes the valve mechanism to disallow return fuel flow to a tank whose sender data indicates that the level of fuel is greater than that indicated by sender data from the sender of another tank by some defined amount.
Another generic aspect of the present invention relates to a method of balancing fuel tanks in a motor vehicle that comprises a fuel-consuming engine for propelling the vehicle and a fuel system for fueling the engine. The fuel system comprises multiple fuel tanks, each for holding liquid fuel for the engine, and for each tank, a respective sender for providing data representing the level of liquid fuel in the respective tank. A pump draws fuel from the tanks through respective fuel draw conduits communicated to the respective tanks and delivers the drawn fuel to the engine. Excess fuel is returned from the engine to each tank through a respective fuel return conduit, with a valve mechanism controlling return fuel flow through the fuel return conduits to the tanks. The method comprises processing the data from the respective senders, and causing the valve mechanism to disallow return fuel flow to a tank whose sender data indicates that the level of fuel is greater than that indicated by sender data from the sender of another tank by some defined amount.
Still another aspect relates to a motor vehicle comprising a fuel-consuming engine for powering the vehicle and a fuel system for fueling the engine, wherein the fuel system comprises two fuel tanks, each for holding liquid fuel for the engine, and each disposed at a respective side of a chassis of the vehicle. For each tank, a respective sender indicates the level of liquid fuel in the respective tank. A pump draws fuel from each tank through a respective fuel draw conduit and delivers the drawn fuel to the engine. Excess fuel is returned to the tanks through respective fuel return conduits. A valve mechanism controlled by the senders disallows return fuel flow to a tank whose sender indicates that the level of fuel is greater than that indicated by the sender of the other tank by some defined amount while the pump continues to draw fuel from both tanks through the fuel draw conduits.
Still another aspect relates to a fuel system of a motor vehicle that is powered by a fuel-consuming engine. The fuel system comprises two fuel tanks, each for holding liquid fuel for the engine, two senders, each for indicating the level of liquid fuel in the respective tank, and an engine-driven pump that is able to simultaneously draw fuel from both tanks and deliver the drawn fuel to the engine so long as the engine is running. The pump draws fuel out of the respective tank through a respective fuel draw conduit. Excess fuel returned from the engine enters a respective tank via a respective fuel return conduit. A valve mechanism controlled by the senders disallows return fuel flow to a tank whose sender indicates that the level of fuel is greater than that indicated by the sender of the other tank by some defined amount while the pump continues to draw fuel from both tanks through the fuel draw conduits.
The foregoing, along with further features and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. This specification includes drawings, now briefly described as follows.